New T-Space Updates

[henryhallam]

Unless you have some sort of super nuclear engine then either direct entry or some form of aerobraking is more or less unavoidable on a lunar return, because you need to lose more than 3km/s to get back to LEO. Think of the size of the S-IVB compared to the Apollo CSM/LM and you get an idea of what sort of rocket you need to give that much dV to a decent mass of spacecraft.<br /><br />In order to aerobrake into LEO on one pass you would need a heatshield almost as substantial as that used for final reentry. So if you're going to come all the way down eventually anyway, you may as well go for direct re-entry.<br /><br /> If you are willing to let the aerobraking take a lot longer - several passes over the course of 2 to 3 months - then you can get away with a much lighter heatshield or none at all by doing the braking high in the atmosphere. This isn't much use for crewed vehicles but could be worthwhile for an Earth-Moon-Earth shuttle or something similar. <br /><br />Or you could go for a combination of the two approaches - some time after trans-Earth injection, a small entry capsule (or lifting body, spacefire <img src="/images/icons/wink.gif" /> ) separates with the crew then the rest of the vehicle caries out a tiny course-correction burn to put it on a multi-pass aerobraking trajectory.

 

[gunsandrockets]

"If you are willing to let the aerobraking take a lot longer - several passes over the course of 2 to 3 months - then you can get away with a much lighter heatshield or none at all by doing the braking high in the atmosphere. This isn't much use for crewed vehicles but could be worthwhile for an Earth-Moon-Earth shuttle or something similar.<br /><br /> Or you could go for a combination of the two approaches - some time after trans-Earth injection, a small entry capsule (or lifting body, spacefire ) separates with the crew then the rest of the vehicle caries out a tiny course-correction burn to put it on a multi-pass aerobraking trajectory."<br /><br />A direct Earth return manned module combined with a slow-aerobraking mothership makes a lot of sense for a Mars mission. Maybe the unmanned mothership could combine aerobraking with lunar flybys to bleed off Delta v as it slowly reduces and circularizes it's orbit around Earth.<br /><br />This flight plan could permit the design of a fully reusable Mars ship. I think that's a much better idea than some plans which assume a Mars ship is wholly expended in one flight.

 

[gunsandrockets]

"Am I right to say that the reason spacecraft are so heavy is because of the components on them that must get them safely back on the ground. If you do away with the need for the vehicle going to the moon to have to land back on the ground, and instead have the CXV do this part, you can lighten the CEV incredibly."<br /><br />"But it seems that every Sci-Fi movie I see has some vehicle based in space at a space station and a Transfer vehicle carries passengers and crew to it. <br /><br />For example, the Orion Spaceplane in 2001 does not travel all the way to the Moon. Instead the passengers transfer to a special Moon vehicle, that does not have the wings not required to land on the Moon."<br /><br />Your instincts are correct, but...(there's always a but!) Things can get complicated, depending depending depending...<br /><br />For example, let's look at the Apollo mission Lunar Excursion Module (LM). The LM was a pure non-Earth vehicle (aside from it's ride into orbit carried by a Saturn V booster). Since it did not have to deal with an atmosphere, typical symmetry and streamlining could be avoided. Since the moon is only 1/6 a gee, the LM structure could be light and delicate, and the engines small and low powered.<br /><br />But the LM still had to deal with the weight of landing gear, and the real advantage of the LM wasn't the non-Earth based design, the real benefit was a way for the Apollo mission to add extra staging, just another way to stretch the mass ratio.<br /><br />Mass ratio is the ratio of the fueled weight of a rocket to it's empty weight. Because of the inherent inefficiencies of rockets and the inefficiency of high thrust to weight chemical rocket engines, vehicles like Saturn/Apollo are almost all fuel tank. Staging is just one way of improving the mass ratio of a rocket.<br /><br />So the real division between your spacecraft, is between your pure space based vehicles and FERRIES (whether the ferry deals with an atmosphere or not). Any ferry will hav

 

[henryhallam]

<font color="yellow"><br />A direct Earth return manned module combined with a slow-aerobraking mothership makes a lot of sense for a Mars mission. Maybe the unmanned mothership could combine aerobraking with lunar flybys to bleed off Delta v as it slowly reduces and circularizes it's orbit around Earth.<br /></font><br /><br />Perhaps but the task is quite a lot harder for something returning from Mars. When returning from lunar orbit you are effectively in a (very high) Earth orbit the whole time, so you can make as many slow aerobraking passes as you like. When returning from Mars the trajectory is hyperbolic with respect to Earth rather than just a very eccentric ellipse. So you must bleed off considerable velocity ON THE FIRST PASS or you won't have a second chance. This leads me to think that you would need to dip quite deep into the atmosphere and therefore would require a fairly hefty heatshield even on the slow-aerobraking mothership.<br />An alternative would be to aerobrake as low as you dare without a heatshield, with the added help of a relatively small rocket burn at perigree, just enough to bring you into a highly elliptical Earth orbit after which you can aerobrake down to LEO at your leisure. This would still result in very significant propellant savings over a solely rocket-based capture into LEO.<br /><br />It is well worth remembering that LEO is halfway to anywhere, but only halfway! And that whatever velocity you add to climb out of LEO, you must get rid of to drop back into it.<br /><br /><font color="yellow"><br />This flight plan could permit the design of a fully reusable Mars ship. I think that's a much better idea than some plans which assume a Mars ship is wholly expended in one flight.<br /></font><br /><br />I tend to agree but you do have to weigh it against the costs of developing and maintaining such a vehicle - remember maintanence must now be done in space, so really you have to design everything from the beginning

 

[nacnud]

There is now an animation of a CXV flight available on their website, here's a link:<br /><br />http://www.transformspace.com/media_gallery/media/CXV_ConOps.mpg<br /><br />Couple of points of interest, the crew boards the CVX from the VLA in flight! That means ejection seats for the crew can be used, if deemed necessary, during VLA takeoff. Secondly look at the size of the expansion nozzle on the first and second stages, its huge! I suppose that is because they are optimized for vacuum, and its a relatively low pressure system, still it is interesting to note.<br />

 

[holmec]

Very nice. It was interesting to me that the rocket was dropped and oriented in a somewhat vertical angle, then the rockets lit. Also that the astronauts can board the capsule just before drop. Thats nice.<br /><br />"Stewardess, Ill have the babacue pork before launch. Thanks." <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[mrmorris]

<font color="yellow">"...pork before launch..."</font><br /><br />Um... do you happen to know that a fairly significant percentage of the population... including veteran astronauts... get space sick upon hitting Zero-G? Might wish to skip that pork. Even if you don't, I feel confident that the other crewmembers wish you would. <img src="/images/icons/smile.gif" />

 

[radarredux]

> <i><font color="yellow">Very nice. It was interesting to me that ...</font>/i><br /><br />From the web page, I found the following interesting:<br /><ul type="square"><li> "Air launching eliminates the need for a fixed ground launch complex"<li> "Most winds and precipitation at the airport runway -- launch site -- don't delay a launch"<li> "The carrier aircraft over open ocean can launch the CXV to any azimuth, and by flying across longitudes, can quickly match a desired orbit phasing"<br /></li></li></li></ul><br /><br />The DOD, which is funding a lot of the seedling work, must love these features: Lauch from almost any place, at any time, to any phase of any azimuth. Hopefully if NASA hesitates at the $400 million, the DOD can step in to help fund some of this.</i>

 

[aaron38]

Man that launch sure looks like a kick in the teeth! From freefall straight to 3G's.<br /><br />Mountain Dew should advertise on it, the new EXTREME thing to do.

 

[dream_on]

Just wanted to point out, with everybody pointing out the advantages of air launch, the major negative:the are practicle upper limits to the vehicle, and therefore payload, size.(Even presupposing a larger aircraft, there would be a restricted number of landing zones to accomadate it, largely negating flexibillity.). This is why SpaceX chose a ground launch;they're looking for scaleabillity from a small half-ton launcher up to their rummored Saturn-scale 'super-gulp' launcher. I doubt that multible missions are ultimately more cost-effective in the long run than a single launch.<br /><br /> This is a textbook example of why we need a diverse commercial market;both approaches will likely have an edge in different situations. I suspect suborbital ventues will likely come to use air-launch as standard, and flexibillity may well remain a signifficant advantage for light and light-medium orbitals, but much beyond that, probably not.(Incidently, I suspect SpaceX among others is working hard on the other solution to launch flexibillity:dissasemble and DRIVE to the site! <img src="/images/icons/laugh.gif" /> )<br /><br /> By the way, what's keeping T-space from competing in DARPA's Falcon program? Their proposal is allmost identical to Airlaunch's(unmanned however)approach!<br /><br /><br /><br /> Joel

 

[radarredux]

> <i><font color="yellow">If DOD does buy this CXV I wonder who will build all of the WhiteNights and so on.</font>/i><br /><br />Ah, I wasn't thinking that the DOD would want a CXV. The DOD has expressed an interest in (1) putting up low-cost spy satellites quickly for a sudden new host spot and (2) replacing an important satellite that was taken out.<br /><br />The t/Space approach is like DARPA's RASCAL or FALCON programs on steroids.<br /><br />See:<br />http://www.aviationnow.com/avnow/news/channel_awst_story.jsp?id=news/09223top.xml<br /><br />http://www.airlaunchllc.com/<br /><br />http://www.darpa.mil/tto/programs/falcon.html<br /><br />http://www.darpa.mil/DARPATech2002/presentations/tto_pdf/speeches/CARTER.pdf<br /></i>

 

[radarredux]

> <i><font color="yellow">By the way, what's keeping T-space from competing in DARPA's Falcon program? Their proposal is allmost identical to Airlaunch's(unmanned however)approach!</font>/i><br /><br />At least two of the t/Space partners, Airlaunch and Scaled, have contracts for FALCON or RASCAL (which I think is now dead). This is what I think DARPA is great for: prototyping new technologies or new approaches.</i>

 

[dream_on]

Ohhhhhh...whoops, should've looked more closely at t-space's partners list. <img src="/images/icons/blush.gif" /> <img src="/images/icons/laugh.gif" /><br /><br /> Ah well, back to waiting for Spacex's august launch... <img src="/images/icons/laugh.gif" /><br /><br /> <br /><br /> Joel<br />

 

[holmec]

Yep. Bring Pepto. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[holmec]

>Um... do you happen to know that a fairly significant percentage of the population... including veteran astronauts... get space sick upon hitting Zero-G? Might wish to skip that pork. Even if you don't, I feel confident that the other crewmembers wish you would. <<br /><br />I know other crew member wish I would, and beans too. I can vividly remember my airborne years in AWACS, if someone was passing gas, it floated from section to section. You could hear its course over the intercom via the reaction of the crew. It was dubbed as the "green cloud". I can only imagine how worse such a thing is in a capule or station.<br /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

 

[mrmorris]

<font color="yellow">"It was dubbed as the "green cloud". "</font><br /><br />Calls to mind something my brother said a lot when we were growing up: "That's about as funny as a fart in a spacesuit."<br /><br />That's gotta really bite. <img src="/images/icons/smile.gif" />

 

[gofer]

More photos of the mock-up http://www.thespacereview.com/gallery/11

 

[gladiator1332]

http://www.thespacereview.com/gallery/11/2<br /><br />That image really has some echos of Big Gemini, with the hatch in the bottom of the spacecraft. It really shows how T/Space was inspired by several programs when drafting up this concept. <br />I am really surprised by the scale of the mock-up as well. I've seen some shots of the interior and the computer generated images, but I have never seen the exterior. Really impressive.<br /><br />Common NASA let them build this bird!

 

[gofer]

23% subscale booster separation tests with help from Rutan: http://www.transformspace.com/index.cfm?fuseaction=news.view&newsid=7BF0B346-96E5-2DD1-938D2A3D296F773A<br /><br />If they indeed are doing all this for $3mil they REALLY know how to manage budgets. (lockmart was doing essentially the same thing with its x-38 for $300mil)

 

[gofer]

Photos: http://www.transformspace.com/index.cfm?fuseaction=media_gallery.viewalbum&albumid=7AAE884D-BB61-80D0-05861B9666624BC0

 

[nacnud]

Well, it seems to work <img src="/images/icons/smile.gif" /> <br /><br /><font color="yellow"><br /> These images, taken at half-second intervals, show the release of a test article built to 23% scale of the CXV capsule and the QuickReach II booster. Three drop tests from May 24 through June 7 proved a new t/Space technique that eliminates the need for wings on air-launched vehicles. The innovation involves a special mechanism that briefly holds on to the nose of the vehicle after the main body is released, starting the vehicle on a slow rotation toward vertical so that its engines can propel the rocket toward orbit. The inert test articles were dropped from the Proteus aircraft operated by Burt Rutan's Scaled Composites.<font color="white"></font></font>

 

[gladiator1332]

I for one do not believe that we have seen the last of T/Space with announcement that either LM or Boeing will be building the CEV.<br />One way or another, I think the CXV will be built.

 

[tap_sa]

<font color="yellow">"Well, it seems to work"</font><br /><br />I really wonder what this peculiar drop method is supposed to solve that ordinary thrust vectoring would't. One thing is sure, it will cause some serious lateral forces when the rocket is flying at almost 90 degrees angle of attack prior to ignition. That would rip ordinary rockets apart in a split second. Don't know how fast VLA/modded 747 will travel at release point but surely it will be a lot more than White Knight's leisurely 115 knots.

 

[nacnud]

The reason for Burt has given for choosing to air launch are that he thinks it is safer then a pad launch to abort from and also so the launch site is less dependent on weather constraints. <br /><br />If flying fast at a release causes all kinds of problems it would be strange to assume that the VLA would be flying fast.<br />

 

[tap_sa]

I meant the TLAD <i>drop</i> method versus just releasing the rocket so that for a moment it will travel horisontally, ignite it's engine and use TVC to turn the nose up while picking up speed.<br /><br />Air launching itself has undeniable benefits, provided that requirements for the aircraft (payload, speed) stay within reasonable limits.